Systemd/networkd: Difference between revisions

Line 25:

can write your complete network setup in native networkd configuration, you should

stay away from that option.

=== network-online.target ===

While <code>network.target</code> only requires the network management stack

to be up, which means it does not care about network interfaces being configured,

the <code>network-online.target</code> waits until a defined set of network

interfaces are in a state, that by its configuration is considered online.

When networkd is enabled, the <code>network-online.target</code> is implemented

through the <code>systemd-networkd-wait-online.service</code>, which makes

sure interfaces configured through networkd are in their expected operational state.

The current operational state of network interfaces can be learned from <code>networkctl</code>.

❯ networkctl

IDX LINK TYPE OPERATIONAL SETUP

1 lo loopback carrier unmanaged

2 enp10s0 ether routable unmanaged

3 wlp9s0 wlan no-carrier unmanaged

</syntaxhighlight>

For most network interfaces that will mean that they have <code>routable</code>

network connectivity, but in more complex setups some links may be content with more

simple states like <code>carrier</code> or <code>enslaved</code>. Interfaces that

are managed by networkd, but not always in use, shouldn't be required for

<code>network-online.target</code>

systemd.network."50-enp3s0" = {

matchConfig.Name = "enp3s0";

# acquire a DHCP lease, when connected

networkConfig.DHCP = "yes";

# this port is not always connected and not required to be online

linkConfig.RequiredForOnline = "no";

};

</syntaxhighlight>

Note that the default value for <code>linkConfig.RequiredForOnline</code> is unexpectedly

<code>"yes"</code>, which often leads to a failing <code>network-online.target</code>.

Setting individual interfaces to <code>"no"</code> is a perfectly valid choice

and should be considered, before disabling the <code>systemd-networkd-wait-online.service</code>

entirely, because a working <code>network-online.target</code> is required for some

services to properly start without race conditions.

Further details in the upstream documentation:

* [https://www.freedesktop.org/software/systemd/man/systemd.network.html#RequiredForOnline= RequiredForOnline=]

* [https://www.freedesktop.org/software/systemd/man/networkctl.html#%0A%20%20%20%20%20%20%20%20%20%20list%0A%20%20%20%20%20%20%20%20%20%20PATTERN%E2%80%A6%0A%20%20%20%20%20%20%20%20 List of operational interface states]

== Examples ==